Choose the Correct Answer

Correct Answer : Option a

Explanation
Discontinuity is the concept of distinct boundaries within the Earth's interior where physical properties like seismic wave velocity change abruptly, marking the separation between different layers of the Earth.
Conrad Discontinuity: This boundary separates the lighter, granitic upper crust (SIAL) from the denser, basaltic lower crust (SIMA).
Moho-Discontinuity: This is the most prominent discontinuity, marking the transition between the Earth's crust and the mantle.
Repetti Discontinuity: This discontinuity separates the upper mantle from the lower mantle.
Gutenberg Discontinuity: This boundary lies between the Earth's mantle and the liquid outer core.
Lehmann Discontinuity: This marks the transition between the liquid outer core and the solid inner core.
Thus, Only the Pair 1 is correct.